Long Term Impact of Biomineralization in Arsenic Fate Under Simulated Landfill Conditions

Persistent Link:
http://hdl.handle.net/10150/333208
Title:
Long Term Impact of Biomineralization in Arsenic Fate Under Simulated Landfill Conditions
Author:
Fathordoobadi, Sahar
Issue Date:
2014
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 04-Aug-2016
Abstract:
Lowering the Maximum Contaminant Level (MCL) for arsenic in drinking water in the U.S., has caused a significant increase in the volume of Arsenic Bearing Solid Residuals (ABSRs) generated by drinking water utilities. Most of the affected utilities are smaller water treatment facilities, especially in the arid Southwest, and are expected to use adsorption onto solid sorbents for arsenic removal. Because of their high adsorption capacity and low cost, iron sorbents are used treatment technology and, when the sorbent's capacity is spent, these ABSRs are disposed in municipal solid waste (MSW) landfills and as a consequence arsenic is likely being released into leachate. However, a mature landfill is a biotic, reducing environment, which causes arsenic reduction and mobilization from the ABSRs. It is well documented that iron and sulfur redox cycles largely control arsenic cycling and, because iron and sulfur are ubiquitous in MSW, it is suspected that they play key roles in arsenic disposition in the landfill microcosm. The purpose of this study is to investigate the degree to which sulfate can prevent arsenic from leaching into landfill through biomineralization and to study ABSRs biogeochemical weathering effect on arsenic sequestration. The primary routes of iron and sulfate reduction in landfills are microbially mediated and biomineralization is a common by-product. In this case, biomineralization is the transformation of ferric (hydr) oxides into ferrous iron phase and sulfate into sulfide minerals such as: siderite (FeCO₃), vivianite (Fe₃(PO₄)₂), iron sulfide (FeS), goethite (α-FeOOH), and realgar (AsS). In this work, long-term microbial reduction and biomineralization of iron, sulfur, and arsenic species are evaluated as processes that both cause arsenic release from landfilled ABSRs and may possibly provide a means to re-sequester As in a recalcitrant solid state. The work uses long-term, continuous flow-through laboratory-scale columns in which controlled conditions similar to those found in a mature landfill prevail. In these simulated landfill column experiments, formation of biominerals, same as those that would naturally occur in typical non-hazardous MSW landfills, will be investigated. The feed contains lactate as the carbon source and primary electron donor, and ferric iron, arsenate, and a range of sulfate concentrations as primary electron acceptors. Our results suggest that biomineralization changes the stability of arsenic through a number of different processes including (i) release of arsenic through reductive dissolution of iron-based ABSRs; and (ii) readsorption/incorporation of released arsenic to secondary biominerals. The influence of biominerals, which have less surface area and adsorption capacity than original AFH, on the retention of arsenic is also investigated in this study. Our results show that the concentration of sulfate fed to the system affects the biomineral formation, and that the relative amounts and sequence of precipitation of biominerals affect the free arsenic concentration that can seemingly be engineered by the concentration of sulfate fed to the system. Comparison between the columns with different sulfate concentrations indicate that inflow sulfate concentration higher than 2.08 mM decreases As mobilization to <50%.
Type:
text; Electronic Dissertation
Keywords:
Arsenic; Arsenic Bearing Solid Residuals (ABSRs); Biomineralization; Sulfate; Vivianite; Environmental Engineering; Amorphous Ferric Hydroxide
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Environmental Engineering
Degree Grantor:
University of Arizona
Advisor:
Ela, Wendell P.; Sáez, A. Eduardo

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleLong Term Impact of Biomineralization in Arsenic Fate Under Simulated Landfill Conditionsen_US
dc.creatorFathordoobadi, Saharen_US
dc.contributor.authorFathordoobadi, Saharen_US
dc.date.issued2014-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.releaseRelease 04-Aug-2016en_US
dc.description.abstractLowering the Maximum Contaminant Level (MCL) for arsenic in drinking water in the U.S., has caused a significant increase in the volume of Arsenic Bearing Solid Residuals (ABSRs) generated by drinking water utilities. Most of the affected utilities are smaller water treatment facilities, especially in the arid Southwest, and are expected to use adsorption onto solid sorbents for arsenic removal. Because of their high adsorption capacity and low cost, iron sorbents are used treatment technology and, when the sorbent's capacity is spent, these ABSRs are disposed in municipal solid waste (MSW) landfills and as a consequence arsenic is likely being released into leachate. However, a mature landfill is a biotic, reducing environment, which causes arsenic reduction and mobilization from the ABSRs. It is well documented that iron and sulfur redox cycles largely control arsenic cycling and, because iron and sulfur are ubiquitous in MSW, it is suspected that they play key roles in arsenic disposition in the landfill microcosm. The purpose of this study is to investigate the degree to which sulfate can prevent arsenic from leaching into landfill through biomineralization and to study ABSRs biogeochemical weathering effect on arsenic sequestration. The primary routes of iron and sulfate reduction in landfills are microbially mediated and biomineralization is a common by-product. In this case, biomineralization is the transformation of ferric (hydr) oxides into ferrous iron phase and sulfate into sulfide minerals such as: siderite (FeCO₃), vivianite (Fe₃(PO₄)₂), iron sulfide (FeS), goethite (α-FeOOH), and realgar (AsS). In this work, long-term microbial reduction and biomineralization of iron, sulfur, and arsenic species are evaluated as processes that both cause arsenic release from landfilled ABSRs and may possibly provide a means to re-sequester As in a recalcitrant solid state. The work uses long-term, continuous flow-through laboratory-scale columns in which controlled conditions similar to those found in a mature landfill prevail. In these simulated landfill column experiments, formation of biominerals, same as those that would naturally occur in typical non-hazardous MSW landfills, will be investigated. The feed contains lactate as the carbon source and primary electron donor, and ferric iron, arsenate, and a range of sulfate concentrations as primary electron acceptors. Our results suggest that biomineralization changes the stability of arsenic through a number of different processes including (i) release of arsenic through reductive dissolution of iron-based ABSRs; and (ii) readsorption/incorporation of released arsenic to secondary biominerals. The influence of biominerals, which have less surface area and adsorption capacity than original AFH, on the retention of arsenic is also investigated in this study. Our results show that the concentration of sulfate fed to the system affects the biomineral formation, and that the relative amounts and sequence of precipitation of biominerals affect the free arsenic concentration that can seemingly be engineered by the concentration of sulfate fed to the system. Comparison between the columns with different sulfate concentrations indicate that inflow sulfate concentration higher than 2.08 mM decreases As mobilization to <50%.en_US
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectArsenicen_US
dc.subjectArsenic Bearing Solid Residuals (ABSRs)en_US
dc.subjectBiomineralizationen_US
dc.subjectSulfateen_US
dc.subjectVivianiteen_US
dc.subjectEnvironmental Engineeringen_US
dc.subjectAmorphous Ferric Hydroxideen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEnvironmental Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEla, Wendell P.en_US
dc.contributor.advisorSáez, A. Eduardoen_US
dc.contributor.committeememberEla, Wendell P.en_US
dc.contributor.committeememberSáez, A. Eduardoen_US
dc.contributor.committeememberArnold, Robert G.en_US
dc.contributor.committeememberChorover, Jonathan D.en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.